The latest launch in the SimCity franchise has met with some rather public failures. Server issues preventing customers from playing the game, saved cities becoming corrupted, immersion breaking AI quirks. Probably the most contentious issue in this whole mess, has been the requirement that players always be online in order to play, even if they only want to play the game single player. This has caused repeated clashes between the long time fans of the series, and the game's developers
A lot of people seem to believe that the only reason for the 'always online' policy is to enforce DRM, preventing piracy at the cost of a worse experience for legitimate customers. SimCity developers countered that the reason for this requirement was that, with the way the game simulation works they needed to do a significant number of the calculations on their own servers; and that it would take a tremendous amount of effort to allow the game to run offline on people's home computers.
This statement turned out to be not at all accurate, as it was found the game can run perfectly fine on home computers without an internet connection.
[Edit - Revisiting this a year later in 2014, the Sim City blog recently released an article
about their efforts to code a single player version of the game. It seems that the online calculations they refereed to were specifically about the cross region communication between cities; not the currently active game play of the cities themselves (Other than the effects other cities might have on you). So while you could play offline, you wouldn't be able to save or interact with other city regions.
It is an interesting read, and shows there is more complexities going on in the coding and design choices then are always made aware to the public. On one hand, it still shows that the original design choices they made was to push a series that had been predominantly single player content to a multi-player online only format. But they have gone to lengths to add that single player content back into the game well after the games release.]
Since then the company has responded by saying while they could have developed an offline mode, they rejected that idea because it did not match their vision of creating a game that moves from single isolated cities to interconnected dependent cities.
While this does not address why they made the original claims about the work their hosted servers were doing, it does raise an interesting question about the artistic vision developers have for a game. Say we discard the anti-piracy theory, and take their new claim about why there is no offline mode at face value...